This application claims the benefit of Japanese Application No. 2001-162590 filed May 30, 2001.
The present invention relates to an ultrasonic imaging method and apparatus, and more particularly to ultrasonic imaging method and apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal.
In ultrasonic imaging, the interior of a subject is repeatedly scanned by an ultrasonic beam sequentially for every acoustic line to receive an echo, and an image frame is produced for each scan based on an echo received signal.
The definition of an image varies with the acoustic line density of the scan. As the acoustic line density becomes dense, the definition is improved; and as the acoustic line density becomes coarse, the definition is reduced. The range of echo intensity representation varies with the dynamic range of the echo reception. As the dynamic range is enlarged, the range of representation is enlarged; and as the dynamic range is reduced, the range of representation is reduced. The SNR (signal-to-noise ratio) of an image varies with the frame averaging intensity. As the frame averaging intensity is raised, the SNR is improved; and as the frame averaging intensity is lowered, the SNR is reduced.
A user of the ultrasonic imaging apparatus conducts imaging after appropriately adjusting the acoustic line density, dynamic range, frame averaging etc. for each imaging purpose. However, since such adjustment largely depends upon the skill of individual users, not every user can conduct imaging in a proper condition.
It is therefore an object of the present invention to provide an ultrasonic imaging method and apparatus by which imaging in a proper condition is facilitated.
(1) The present invention, in accordance with one aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; increasing the acoustic line density of the scan in response to an increase of the correlation value; and decreasing the acoustic line density of the scan in response to a decrease of the correlation value.
(2) The present invention, in accordance with another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; and acoustic line density adjusting means for increasing the acoustic line density of the scan in response to an increase of the correlation value and decreasing the acoustic line density of the scan in response to a decrease of the correlation value.
In the invention of the aspects described in (1) and (2), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; and the acoustic line density of the scan is increased in response to an increase of the correlation value, and is decreased in response to a decrease of the correlation value.
The correlation value increases with a smaller difference between the two image frames, i.e., a smaller temporal change of the image. Therefore, by increasing the acoustic line density to improve the image definition, precise imaging can be achieved for a slow-moving subject.
On the other hand, the correlation value decreases with a larger difference between the two images frames, i.e., a larger temporal change of the image. Therefore, by decreasing the acoustic line density to increase the frame rate of the image, imaging with good temporal resolution can be achieved for a fast-moving subject.
(3) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; enlarging the dynamic range of the echo reception in response to an increase of the correlation value; and reducing the dynamic range of the echo reception in response to a decrease of the correlation value.
(4) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; and dynamic range adjusting means for enlarging the dynamic range of the echo reception in response to an increase of the correlation value, and reducing the dynamic range of the echo reception in response to a decrease of the correlation value.
In the invention of the aspects described in (3) and (4), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; and the dynamic range of echo reception is enlarged in response to an increase of the correlation value, and is reduced in response to a decrease of the correlation value.
The correlation value increases with a smaller difference between the two image frames, i.e., a smaller temporal change of the image. Therefore, by enlarging the dynamic range to enlarge the range of echo intensity representation, precise imaging can be achieved for a slow-moving subject.
On the other hand, the correlation value decreases with a larger difference between the two images frames, i.e., a larger temporal change of the image. Therefore, by reducing the dynamic range to reduce the range of echo intensity representation, simplified imaging can be achieved for a fast-moving subject.
(5) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; raising the frame averaging intensity of the image frame in response to an increase of the correlation value; and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
(6) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; and frame averaging adjusting means for raising the frame averaging intensity of the image frame in response to an increase of the correlation value, and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
In the invention of the aspects described in (5) and (6), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; and the frame averaging intensity of the image frame is raised in response to an increase of the correlation value, and is lowered in response to a decrease of the correlation value.
The correlation value increases with a smaller difference between the two image frames, i.e., a smaller temporal change of the image. Therefore, by raising the frame averaging intensity to improve the SNR of the image, precise imaging can be achieved for a slow-moving subject.
On the other hand, the correlation value decreases with a larger difference between the two images frames, i.e., a larger temporal change of the image. Therefore, by lowering the frame averaging intensity to improve the responsiveness to a change, imaging with good temporal resolution can be achieved for a fast-moving subject.
(7) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; increasing the acoustic line density of the scan in response to an increase of the correlation value; decreasing the acoustic line density of the scan in response to a decrease of the correlation value; enlarging the dynamic range of the echo reception in response to an increase of the correlation value; and reducing the dynamic range of the echo reception in response to a decrease of the correlation value.
(8) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; acoustic line density adjusting means for increasing the acoustic line density of the scan in response to an increase of the correlation value, and decreasing the acoustic line density of the scan in response to a decrease of the correlation value; and dynamic range adjusting means for enlarging the dynamic range of the echo reception in response to an increase of the correlation value, and reducing the dynamic range of the echo reception in response to a decrease of the correlation value.
In the invention of the aspects described in (7) and (8), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; and the acoustic line density of the scan is increased and the dynamic range of the echo reception is enlarged in response to an increase of the correlation value; and the acoustic line density is decreased and the dynamic range is reduced in response to a decrease of the correlation value.
Therefore, by increasing the acoustic line density to improve the image definition, and enlarging the dynamic range of the echo reception to enlarge the range of echo intensity representation, precise imaging can be achieved for a slow-moving subject.
Moreover, by decreasing the acoustic line density to increase the frame rate of the image, and reducing the dynamic range of the echo reception to reduce the range of echo intensity representation, simplified imaging with good temporal resolution can be achieved for a fast-moving subject.
(9) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; increasing the acoustic line density of the scan in response to an increase of the correlation value; decreasing the acoustic line density of the scan in response to a decrease of the correlation value; raising the frame averaging intensity of the image frame in response to an increase of the correlation value; lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
(10) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; acoustic line density adjusting means for increasing the acoustic line density of the scan in response to an increase of the correlation value, and decreasing the acoustic line density of the scan in response to a decrease of the correlation value; and frame averaging adjusting means for raising the frame averaging intensity of the image frame in response to an increase of the correlation value, and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
In the invention of the aspects described in (9) and (10), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; the acoustic line density of the scan is increased and the frame averaging intensity of the image frame is raised in response to an increase of the correlation value; and the acoustic line density is decreased and the frame averaging intensity is lowered in response to a decrease of the correlation value.
Therefore, by increasing the acoustic line density to improve the image definition, and raising the frame averaging intensity to improve the SNR of the image, precise imaging can be achieved for a slow-moving subject.
Moreover, by decreasing the acoustic line density to increase the frame rate of the image, and lowering the frame averaging intensity to improve the responsiveness to a change, imaging with good temporal resolution can be achieved for a fast-moving subject.
(11) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; enlarging the dynamic range of the echo reception in response to an increase of the correlation value; reducing the dynamic range of the echo reception in response to a decrease of the correlation value; raising the frame averaging intensity of the image frame in response to an increase of the correlation value; and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
(12) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; dynamic range adjusting means for enlarging the dynamic range of the echo reception in response to an increase of the correlation value, and reducing the dynamic range of the echo reception in response to a decrease of the correlation value; and frame averaging adjusting means for raising the frame averaging intensity of the image frame in response to an increase of the correlation value, and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
In the invention of the aspects described in (11) and (12), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; dynamic range of echo reception is enlarged and the frame averaging intensity of the image frame is raised in response to an increase of the correlation value; and the dynamic range is reduced and the frame averaging intensity is lowered in response to a decrease of the correlation value.
Therefore, by enlarging the dynamic range to enlarge the range of echo intensity representation, and raising the frame averaging intensity to improve the SNR of the image, precise imaging can be achieved for a slow-moving subject.
Moreover, by reducing the dynamic range to reduce the range of echo intensity representation, and lowering the frame averaging intensity to improve the responsiveness to a change, simplified imaging with good temporal resolution can be achieved for fast-moving subject.
(13) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging method for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising the steps of: calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; increasing the acoustic line density of the scan in response to an increase of the correlation value; decreasing the acoustic line density of the scan in response to a decrease of the correlation value; enlarging the dynamic range of the echo reception in response to an increase of the correlation value; reducing the dynamic range of the echo reception in response to a decrease of the correlation value; raising the frame averaging intensity of the image frame in response to an increase of the correlation value; and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
(14) The present invention, in accordance with still another aspect for solving the aforementioned problem, is an ultrasonic imaging apparatus for repeatedly scanning the interior of a subject by an ultrasonic beam sequentially for every acoustic line to receive an echo, and producing an image frame for each scan based on an echo received signal, comprising: correlation value calculating means for calculating a correlation value between a new image frame and a previous image frame each time the new image frame is obtained; acoustic line density adjusting means for increasing the acoustic line density of the scan in response to an increase of the correlation value, and decreasing the acoustic line density of the scan in response to a decrease of the correlation value; dynamic range adjusting means for enlarging the dynamic range of the echo reception in response to an increase of the correlation value, and reducing the dynamic range of the echo reception in response to a decrease of the correlation value; and frame averaging adjusting means for raising the frame averaging intensity of the image frame in response to an increase of the correlation value, and lowering the frame averaging intensity of the image frame in response to a decrease of the correlation value.
In the invention of the aspects described in (13) and (14), a correlation value is calculated between a new image frame and a previous image frame each time the new image frame is obtained; the acoustic line density of the scan is increased, the dynamic range of the echo reception is enlarged, and the frame averaging intensity is raised in response to an increase of the correlation value; and the acoustic line density is decreased, the dynamic range is reduced, and the frame averaging intensity is lowered in response to a decrease of the correlation value.
Therefore, by increasing the acoustic line density to improve the image definition, enlarging the dynamic range to enlarge the range of echo intensity representation, and raising the frame averaging intensity to improve the SNR of the image, precise imaging can be achieved for a slow-moving subject.
Moreover, by decreasing the acoustic line density to increase the frame rate of the image, reducing the dynamic range to reduce the range of echo intensity representation, and lowering the frame averaging intensity to improve the responsiveness to a change, simplified imaging with good temporal resolution can be achieved for a fast-moving subject.
Preferably, the image frames for use in the calculation of the correlation value are those obtained by averaging a plurality of consecutive image frames, because the stability of the correlation value is improved.
As described above in detail, the present invention can provide an ultrasonic imaging method and apparatus by which imaging in a proper condition is facilitated.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.